Flow measuring device



Oct. 1, 1968 N. c. KOESTER 3,403,556

FLOW MEASURING DEVICE Filed July 15, 1966 I I l 742 I 72%} fig \\jMENTOR 72 7707mm? C Kosier m 4. BY

ATTORNEYS.

United States Patent 3,403,556 FLOW MEASURING DEVICE Norman C. Koester,Lancaster, N.Y., assignor, by mesne assignments, to Automatic SprinklerCorporation, Cleveland, Ohio, a corporation of Ohio Filed July 13, 1966,Ser. No. 564,981 8 Claims. (Cl. 73--207) ABSTRACT OF THE DISCLOSURE Acoil spring providing a flow passage through its convolutions flexes inresponse to variations in pressure differential between the upstream anddownstream portions, thereby varying the flow passage area in accordancewith the flow rate therethrough.

This invention relates to the flow measuring art, and in particular to aflow meter of the restricted orifice type having a variable area orificeadapted to measure rate of flow throughout a wide range of volumetricflow rates.

Generally, the capacity of flow meters to measure both high and lowvolumetric flow rates is severely limited and conventional flow metersmeasure flow rates eflectively only within a relatively small range ofmaximum and minimum volumetric flow rates. Flow rate measurement, in aparticular application, depends on an estimate of the flow rate and thechoice of a flow meter having a measuring range including such estimate.Thus, continuous volumetric flow rate measurements in flow conduitshaving varying volumetric flow rates throughout a wide range heretoforewould often not be obtained utilizing a single flow meter.

Moreover, many flow meters have non-linear responses when operatingclose to the maximum or minimum designed range giving inaccurate -flowrate measurements at these points. Additionally, some flow meters becomeclogged by particles entrained in the flow adhering to the workingsurfaces thereof, causing inaccurate volumetric flow rate measurements.

-In the restricted orifice type of flow meter, to provide a pressuredifferential across the orifice capable of meaningful measurement on amanometer or a differential pressure gauge, a large volume flow raterequires a corresponding large orifice and a small volume flow raterequires a small orifice. A low volumetric flow rate with a largeorifice produces a negligible pressure differential requiring anextremely accurate and often more complex pressure dilferential gauge.Conversely, a large volumetric flow rate with a small orifice increasesthe back pressure to an extent such that the pressure differential nolonger reflects the true volumetric rate of flow. The ideal conditiontherefore approximates an orifice area in direct proportion to thevolumetric flow rate.

Accordingly, a primary object of the present invention is to provide aflow meter having a variable area orifice responsive to the volume rateof flow thereby adapting the flow meter for flow rate measurements overa significantly wider range of flow rates. In a preferred form of myinvention, this is accomplished by the provision of a helically woundspring supported internally of a flow conduit for flexing axially in thedirection of flow to vary the spacing between the spring convolutions,such spacing constituting a variable orifice through which the flowpasses.

It is also an object of the present invention to provide a variableorifice area flow meter having a substantially linear responsethroughout the measuring range thereof.

It is another object of the present invention to provide 3,403,556Patented Oct. 1, 1968 ICC a variable orifice area flow meter which isself-cleaning and will continuously remain free of clogging material.

A further object of the present invention is to provide a variableorifice area flow meter having means for adjusting the orifice area fora given pressure differential to provide greater accuracy in pressuremeasurement during anticipated large or small flow rates.

Various other novel details of construction and advantages inherent inthe flow meter construction of the present invention are pointed out indetail in conjunction with the following description and accompanyingdrawing of two typical embodiments of the invention. It is to beunderstood that such embodiments are by way'of example only and toillustrate the principles of the present invention, the scope of whichis limited only as defined in the appended claims.

In the drawing:

FIG. 1 is a vertical longitudinal sectional view of a flow meter made inaccordance with the present invention;

FIG. 2 is a transverse sectional view thereof, taken about on line 22 ofFIG. 1;

FIG. 3 is an end elevational view of the orifice spring from theupstream side thereof; and

FIG. 4 is a vertical longitudinal sectional view of another embodimentof my invention.

Referring now to FIGS. 1 and 2 of the drawing, there is shown a flowmeter of my invention, generally designated 1. Flow meter 1 comprises atubular housing 3 having a bore therethrough and a sleeve 5telescopingly received within an enlarged diametral portion of the boreat one end of housing 3. Flow meter 1 is adapted for insertion in afluid line, not shown, with the left side thereof, as seen in FIG. 1,being the input and the reduced diameter portion 7 on the right sidethereof, as seen in FIG. 1, forming an outlet. An annular plate 9 issecured within flow meter 1 between the inner end of sleeve 5 and aninternal shoulder 8 formed on housing 3 by the enlarged bore portionthereof, sleeve 5 being suitably seated and secured within housing 3 andagainst plate 9 by sealing gaskets 4 and set screw 6 respectively. Plate9 has a central opening passing axially therethrough of a sizesufficient to cause a measurable pressure drop across the plate as morefully described hereinafter.

Conventional pressure measuring taps 11 communicate through the wallhousing 3 with the fluid passage on opposite sides of plate 9, the tapon the upstream side thereof communicating with the flow passage througha hole 10 in sleeve 5. Sleeve 5 has an external annular groove 12forming with housing 3 a conduit providing communication betweenupstream tap 11 and hole 10 in the event of radial misalignmenttherebetween. Taps 11 communicate with manometers or a pressure gauge,not shown, calibrated to translate the pressure drop across plate 9 intovolume of flow per unit time. The direction of flow is indicated byarrows in FIGS. 1 and 4. If only the fixed orifice of plate 9 wereprovided, the flow meter would be accurate only over a limited range.However, it is a particular feature of my invention that the orificearea varies to accommodate variations in rates of flow. This isaccomplished by providing a linearly variable, pressure differentialelement.

In the embodiment of FIGS. 1-3, this is provided by a cylindrical,helically wound spring 13 adjustably mounted on plate 9. Spring 13' hasan end wall in the form of a plate or diaphragm 15 secured on thedownstream end thereof, closing that end of spring 13. The diameter ofspring 13 is slightly larger than the diameter of the opening throughplate 9. The inner periphery of plate 9 defining the openingtherethrough. has a slot 16 with an adjacent chamfered edge 18 as seenin FIG. 2. By passing the upstream end portion 14 of spring 13 throughslot 16 and engaging the chamfered edge 18, relative rotation of plate 9and spring 13 causes the spring convolutions to wind from the downstreamside of plate 9 through slot 16 to the upstream side thereof. Spring 13is, in effect, screwed onto plate 9' and since chamfered edge 18 forms alarger angle with plate 9 than each spring convolution does, the springfrictionally bears against edge 18 and is thereby maintained in thedesired axial position relative to plate 9. Therefore, the number ofspring convolutions between plate 9 and end plate can be varied andaccordingly the number of spaces between adjacent convolutions on thedownstream side of plate 9 is likewise varied. The upstream end 14 ofspring 13 extends on a diameter, crosswise of the flow passage, and canbe grasped by an appropriate tool for rotary adjusting of spring 13after installation thereof in housing 3.

It is a significant feature of the present invention that the spacingsbetween adjacent spring convolutions on the downstream side of plate 9constitute an orifice having a variable area, and that such variablearea orifice enlarges and contracts in direct proportion to thevolumetric flow rate. The spacing between adjacent convolutions on thedownstream side of plate 9 enlarges or contracts as spring 13 flexesunder the influence of the pressure differential across end plate 15.With high flow rates, the pressure differential increases causing spring-13 to expand axially, thereby increasing the spacing between adjacentconvolutions and enlarging the total area of the orifice providedthereby. Conversely, with low flow rates the pressure differentialdecreases, and spring 13 contracts and decreases the spacing between itsconvolutions, thereby decreasing the total orifice area. Where theapproximate flow rate is known, the spring may be screwed or unscrewedand thereby adjusted axially relative to plate 9 to provide acorrespondingly fewer or greater number of convolutions on thedownstream side thereof, to provide an initial orifice area and a springresponse rate best suited to that flow rate, for extremely accuratemeasurements.

The embodiment depicted in FIG. 4 comprises a flow meter generallydesignated 21 having input and outlet sides 23 and 25 respectively. Aremovable sleeve 27 having smooth and slightly inwardly tapered surfacesprovides a restriction 29 within flow meter 21. Pressure measuring taps31, similar to taps 11 of the previous embodiment, are positioned onopposite sides of restriction 29.

A spring 33, comprising a flat helical coil is positioned transverselywithin flow meter 21 across restriction 29, being mounted in an interiorperipheral slot formed within sleeve 27. Like spring 13 of the precedingembodiment, the spacing between adjacent convolutions of spring 33constitutes an orifice with the area thereof being selfadjustable indirect proportion to the volumetric flow rate. As the rate of flowincreases, the pressure differential across spring 33 increases causingspring 33 to expand in a downstream direction in direct proportion tothe volume of flow, as indicated by the broken line showing thereof inFIG. 4. Such expansion of spring 33 causes the spacing between adjacentconvolutions to increase with resulting enlargement of the area of theorifice. With lower rates of flow the pressure differential decreasesand spring 33 is maintained more planar. In such configuration, spring33 has very close spacing between adjacent convolutions resulting in anorifice having a small area.

In both embodiments, the pressure difference is continuously measuredthrough taps 11 and 31 and translated into volumetric flow ratemeasurements by differential pressure gauges or manometers, not shown,in a manner well understood in the art. It will be noted that therestrictions in the flow passages provided by plate 9 and sleeve 27 aresufficiently large that a flow rate measurement may be taken for verylarge volume rates of flow. The variable area orifice comprising thespacings between the spring convolutions further restricts the flow withthe orifice ranging between areas about as large as the area of therestrictions for high volume flow rates and relatively small areas forlower volume flow rates.

Significantly, the spring provides a self-cleaning action. Materialswhich might tend to clog a flow meter do not normally adhere to thesurfaces of the wire forming the springs 13, 33 and the flexing actionthereof tends to clear any material which might happen to adhere to suchsurface.

It is apparent that I have fully accomplished the objects of myinvention by providing a self-cleaning, selfadjustable flow meter havinga variable area orifice responsive to changes in volumetric fiow ratesto enlarge or contract the area of the orifice for measuring flow ratesover a wide range thereof.

Having fully disclosed and completely described my invention, and itsmode of operation, what I claim as new is:

1. A flow meter comprising means providing a fluid flow passage, andmeans providing a restricted orifice in said passage, said last-namedmeans including a linearly variable pressure differential elementautomatically oper able in response to variations in pressuredifferential thereacross to correspondingly vary the cross-sectionalarea of said orifice, wherein said element comprises a coil springdisposed in said flow passage with all of the fluid flowing through saidpassage flowing through said spring, said spring providing a flowpassage through the convolutions thereof and flexing in response tovariations in pressure differential between the upstream and downstreamportions thereof, thereby varying the area of said flow passage throughsaid spring in accordance with flow rate therethrough.

2. A flow meter comprising means providing a fluid flow passage, andmeans providing a restricted orifice in said passage, said last-namedmeans including a linearly variable pressure differential elementautomatically operable in response to variations in pressuredifferential thereacross to correspondingly vary the cross-sectionalarea of said orifice, wherein said element comprises a coil springdisposed in said flow passage, said spring providing a flow passagethrough the convolutions thereof and flexing in response to variationsin pressure differential between the upstream and downstream portionsthereof, thereby varying the area of said flow passage through saidspring in accordance with flow rate therethrough, together with pressuresensing means communicating with said first-mentioned passage upstreamand downstream of said element.

3. A flow meter according to claim 2 wherein said spring comprises ahelically wound cylindrical spring with the axis thereof extendinglongitudinally of said flow passage.

4. A flow meter according to claim 3, including means closing thedownstream end of said cylindrical spring.

5. A flow meter according to claim 3, wherein said spring is adjustablymounted in said passage intermediate the ends of said spring.

6. A flow meter comprising means providing a fluid flow passage, andmeans providing a restricted orifice in said passage, said last-namedmeans including a linearly variable pressure differential elementautomatically operable in response to variations in pressuredifferential thereacross to correspondingly vary the cross-sectionalarea of said orifice, wherein said element comprises a coil springdisposed in said flow passage, said spring providing a flow passagethrough the convolutions thereof and flexing in response to variationsin pressure differential between the upstream and downstream portionsthereof, thereby varying the area of said flow passage through saidspring in accordance with flow rate therethrough, wherein said springcomprises a helically wound cylindrical spring with the axis thereofextending longitudinally of said flow passage, together with mountingmeans for said spring including a plate extending crosswise of saidfirst mentioned passage and having an opening therethrough providing arestriction in said passage, said plate being engaged between theconvolutions of said spring for adjustably mounting said springintermediate its ends.

7. A flow meter comprising means providing a fluid flow passage, andmeans providing a restricted orifice in said passage, said last-namedmeans including a linearly variable pressure dilferential elementautomatically operable in response to variations in pressuredifferential thereacross to correspondingly vary the cross-sectionalarea of said orifice, wherein said element comprises a coil springdisposed in said flow passage, said spring providing a flow passagethrough the convolutions thereof and flexing in response to variationsin pressure differential between the upstream and downstream portionsthereof, thereby varying the area of said flow passage through saidspring in accordance with flow rate theretli'rough,

wherein said spring is a substantially flat helically wound coilnormally disposed substantially in a transverse plane across saidfirst-mentioned flow passage.

8. A flow meter as set forth in claim 2, wherein said means providing apassage comprise a housing having a bore and a sleeve extending intosaid bore, and wherein said pressure sensing means include a radialpassage through the wall of said sleeve, a radial passage through thewall of said housing, and a circumferential passage between said housingand said sleeve, said circumferential and radial passages being alinedaxially of said meter and said circumferential passage maintainingcommunication between said radial passages during radial misalinementthereof.

References Cited UNITED STATES PATENTS 6/1960 Streeter 73210 4/1961 Mainet al. 73207 U.S. DEPARTMENT OF COMMERCE PATENT OFFICE Washington, 0.0.20231 UNITED STATES PATENT OFFICE CERTIFICATE OF; CORRECTION Patent No.3,403,556 October 1, 1968 Norman C. Koester It is certified that errorappears in the above identified patent and that said Letters Patent arehereby corrected as shown below:

In the heading to the printed specification, line 4, ""AutomaticSprinkler Corporation" should read "Automatic" Sprinkler Corporation ofAmerica Signed and sealed this 24th day of February 1970.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

